A new species of soft scale (Hemiptera: Coccomorpha; Cocccidae) from South Africa, Coccus giliomeei Łagowska Hodgson sp. n., collected on Gymnosporia buxifolia (L.) Szyszyl, is described and illustrated. Also, Coccus rhodesiensis (Hall) is recorded for the first time from South Africa and is redescribed and illustrated based on the adult females of the type series and fresh South African specimens. An updated key to the species of Coccus and similar species known from Africa is included. Based on this latter study, (i) Marsipococcus proteae (Brain) and M. durbanensis (Brain) are considered not to be congeneric with Marsipococcus marsupialis (Green), the type species of Marsipococcus Cockerell Bueker, and are placed in a new genus Proteacoccus Łagowska Hodgson, gen. n. with Lecanium proteae Brain as the type species; (ii) it is considered that Coccus asiaticus Lindinger is clearly not a junior synonym of Parasaissetia nigra (Nietner) and is accepted as a full species, rev. stat., and (iii) Neoplatylecanium adersi (Newstead) is considered to be non-conspecific with N. cinnamomi Takahashi, the type species of Neoplatylecanium Takahashi, and is transferred to Maacoccus Tao Wong, as Maacoccus adersi (Newstead), comb. n.